Tired of touring and promotional interviews, Alexander disbanded the group in mid-1999 before the release of their second single, "Someday We'll Know", to focus on writing and producing songs for other artists. Alexander and Brisebois' songwriting partnership continued following the disbanding of the group, with the two being nominated for the Academy Award for Best Original Song in 2015 for their composition "Lost Stars" from the film Begin Again.

New Radicals had a "revolving door policy" and no permanent members other than Gregg Alexander, who produced, wrote, sang and played various instruments for the band. The only other person considered a relatively constant member was former child actressDanielle Brisebois (All in the Family, Archie Bunker's Place).[6] She acted as background singer, keyboardist and percussionist on the album, at live shows and in the band's music videos. She also co-wrote their second single "Someday We'll Know" with Alexander and Debra Holland. Brisebois had previously worked with Alexander on his 1992 album Intoxifornication and on her 1994 solo debut Arrive All Over You, and was concurrently working with him on her solo album Portable Life at the time (which was not officially released until 2008).

New Radicals was formed in Los Angeles, California in 1997 by Gregg Alexander, who had previously released two unsuccessful solo albums, 1989's Michigan Rain and 1992's Intoxifornication. Michael Rosenblatt, MCA Records' A&R Senior Vice President, signed the band to the label in 1998,[8] and Alexander received a $600,000 advance for their first (and only) album, Maybe You've Been Brainwashed Too.[9] The album was released on October 20, 1998, and was well received by music critics, who praised the record for its wide range of atypical influences for a modern pop-rock album, such as Todd Rundgren, World Party and Hall & Oates, and compared its funk and soul-influenced upbeat pop rock to the early work of Prince and Mick Jagger.

Some critics, however, disliked the album's themes—Alexander's criticism of society and the frequent references to drugs and sex that run throughout the album—denoting them as "shallow posturing" and "empty social pronouncements",[10] while others found that Alexander's social criticism and observations "would sound clichéd if they werent [sic] so insightful and articulated with such uninhibited truth."[11] Also popular with the general audience, the album reached No. 10 on the UK Albums Chart and No. 41 on the Billboard 200 in the U.S., where it also achieved platinum status (1,000,000 copies sold). It was also certified gold in the United Kingdom (100,000 copies sold) and in Canada (50,000 copies sold).

When asked about it in an interview, Marilyn Manson replied he was "not mad that [Alexander] said he'd kick my ass, I just don't want to be used in the same sentence with Courtney Love" and would "crack his skull open if I see him."[4] Beck reported that "I was in a grocery store and he [Alexander] came running up to me, so apologetic, and saying, 'I hope you weren't offended. It wasn't supposed to be personal.' I was kind of pleased, because he's a big guy."[5] Hanson (the band, not to be confused with Beck's last name) said they weren't really bothered by the song, as they saw it as just a pop-culture reference. They also co-wrote the song "Lost Without Each Other" from their 2004 album Underneath with Alexander. Zac Hanson said that "It was cool working with Gregg... [he]'s definitely a character but he's a cool guy."[14]

Following the mass media's excitement about the celebrity insults, Alexander explained that the verse, along with the lines directly preceding it ("Health insurance rip off lying / FDA big bankers buying / Fake computer crashes dining / Cloning while they're multiplying") were an experiment to see if the media would focus on the real issues, or on the celebrity ridicule.[2] Similar complaints and attacks on Christian religion, American society, politics and corporations can be found in other songs on the album as well, and Alexander would often use promotional interviews to talk about these topics, complaining about—among other things—corrupt, greedy politicians and corporate officers, credit card interest, the poor American social security system, and lack of education.[3]

The drums on the album's title track were sampled from the XTC song 'All of a Sudden' (from their English Settlement album). According to XTC's songwriter Andy Partridge, "the sample was used without permission" and the band and its record company eventually received £70,000 in compensation for its use.

When the band canceled their appearance at the Atlanta open-air music festival RockFest, as well as their UK tour (scheduled to start on May 17, 1999), rumors started they would break up, while MCA Records claimed an unspecified member of the band (although explicitly not Alexander) being ill was the cause for the canceled shows.[15] The New Radicals went on to shoot the video for their second single "Someday We'll Know"; however, less than two weeks before its release, Gregg Alexander issued a press release on July 12, announcing the breakup of the group. Alexander said that the New Radicals "will no longer be a recording, promoting, or performing entity" and that he would focus on producing and writing material for other artists. He went on to say that he "accomplished all of [his] goals with this record" and that "the fatigue of traveling & getting three hours sleep in a different hotel every night to do boring 'hanging and schmoozing' with radio and retail people, is definitely not for [him]", that he "lost interest in fronting a 'One Hit Wonder' to the point that [he] was wearing a hat while performing so that people wouldn't see [his] lack of enthusiasm" and that he would go on to form a production company to focus on producing and writing songs freelance for other artists.[16] His first production work after the New Radicals' breakup was the album Portable Life by fellow Radical Danielle Brisebois, originally set to be released in October 1999, but cancelled by RCA Records until eventually being released digitally almost a decade later in September 2008. Given the band's breakup and the resulting lack of promotion, "Someday We'll Know" failed to have a notable impact on the charts (it did not chart the Billboard Hot 100 and reached only No. 28 on the U.S. Adult Top 40 and No. 48 on the UK Singles Chart)

Although no third single was released, there are some (conflicting) clues as to what would have been the third single: Certain promotional copies of Maybe You've Been Brainwashed Too come with a sticker reading "includes 'You Get What You Give', 'I Don't Wanna Die Anymore' and 'Someday We'll Know'",[17] suggesting that "I Don't Wanna Die Anymore" would join the other two as a single release. Several websites selling the album also marked the track as "Album Version", indicating that there would be a single version at some point.[18] However, there also exist copies of "Mother We Just Can't Get Enough" as both a one-track promotional single[19] and as a four-track commercial single with a barcode.[20] These apparently never made it to retail and were probably test pressings.

In addition to the songs released on the United States version of Maybe You've Been Brainwashed Too, two additional studio songs by the New Radicals were produced. The song "To Think I Thought" was included as the B Side to "You Get What You Give" and as an additional track on the Japanese version of the album, and "The Decency League" was a B-side to the single "Someday We'll Know."

In 2003, a new Gregg Alexander song entitled "A Love Like That" was released at PickTheHits.com, a website where users could rate new music. While it was uncredited, fans immediately recognized Alexander's voice and parts of the lyrics that had already appeared in the booklet for Maybe You've Been Brainwashed Too. The song was (as official sites listing Alexander's song repertoire reveal) written by Alexander and Rick Nowels.[21]

In 2005, LMC performed a remix of "You Get What You Give" under the title "Don't Let Go". A new version of the remix, with new vocals by Rachel MacFarlane replacing the samples from the original version, was released in January 2006 as a single under the song's original title. The remix with new vocals peaked at No. 30 on the UK Singles Chart. Shawnna's 2006 song "Chicago" from the album Block Music samples the opening line from Moore and Foreman's version of "Someday We'll Know". In 2013, Brooklyn-based pop-rock duo Savoir Adore covered "You Get What You Give" as part of season four of The A.V. Club's web series A.V. Undercover.[23]